1. Field of the Invention
The invention is directed to the field of electrical voltage surge protection and more particularly to providing surge protection for data communication circuits.
2. Description of the Prior Art
Prior art surge protectors for programmable logic controllers (PLC""s) or similar devices, are complex to use and require the attachment of various grounds, conductors and jumpers to protect data communication circuits. This makes the replacement of the surge protector difficult and time consuming.
The instant invention overcomes the difficulties noted above with respect to the prior art. The instant invention employs a housing with two complementary ground connects. The first is a notched plate capable of accepting the shaft of an attachment bolt. This bolt fastens the housing ground plate to a ground system. The second ground connection is implemented via a low impedance ground strap. The ground strap is used when dimensional constraints prevent the direct bolting of the notched plate to a ground system. The input data conductors are coupled to a plug-in connector which is received in a suitable header on the housing. The output data conductors are also coupled to a plug-in connector which is received in a suitable header on the housing. The use of the plug-in connectors makes the connection to and from the module quick and easy. A number of diode steering bridges couples selected lines to a silicon avalance diode (SAD) which provides surge protection to one another to protect against surges, line to line, and line to ground. The SAD mounted at the bridge output is the surge suppression element for transient voltage surges. Certain of the input data lines are also fused with automatically resettable positive temperature co-efficient devices contained in the housing.